使用数据注释进行自定义验证

Question

我在使自定义数据注解工作时遇到问题，我试图添加验证属性来验证Customer（CustomerID）的UsergroupName是唯一的。

[MetadataType(typeof(UsergroupMetaData))] 
public partial class Usergroup { } 

public class UsergroupMetaData 
{ 
    [Required()] 
    public object CustomerID { get; set; } 

    [Required(ErrorMessageResourceType = typeof(Resources), ErrorMessageResourceName = "UsergroupNameRequired")] 
    public object UsergroupName { get; set; } 

    [UniqueUsergroupName(????)] 
    // what to put here? 
} 



public class UniqueUsergroupName : ValidationAttribute 
{ 
    UsergroupRepository _rep = new UsergroupRepository(); 

    public override bool IsValid(object value, int customerID) 
    { 
     var x = _rep.GetUsergroups().ByUsergroupName(value).ByCustomerID(customerID); 

     // what to put here? 

     return false; 
    } 
} 

如果“count> 0”，IsValid应返回false。

我该如何解决这个问题，以便它能正常工作。 GetUsergroups（）返回IQueryable。

编辑：

[MetadataType(typeof(UsergroupMetaData))] 
public partial class Usergroup { } 

public class UsergroupMetaData 
{ 
    public object CustomerID { get; set; } 

    [Required(ErrorMessageResourceType = typeof(Resources), ErrorMessageResourceName = "UsergroupNameRequired")] 
    [UniqueUsergroupName(ErrorMessageResourceType= typeof(Resources), ErrorMessageResourceName = "UsergroupNameExists")] 
    public object UsergroupName { get; set; } 


} 


public class UniqueUsergroupName : ValidationAttribute 
{ 

    UsergroupRepository _rep = new UsergroupRepository(); 

    public override bool IsValid(object value, int customerID) 
    { 

     int usergroups = _rep.GetUsergroups().ByCustomerID(customerID).ByUsergroupName(value.ToString()).Count(); 

     return usergroups >0; 
    } 
} 

如何传递当前的客户ID作为参数？

/M

Answer 1

你可以把这个方法
http://byatool.com/mvc/custom-data-annotations-with-mvc-how-to-check-multiple-properties-at-one-time/
为了在你的搜索ID属性，让你检查所有的“其他” UsergroupMetaData 具有相同UsergroupName。

如果您无法将其应用于您的场景，请检查并联系我。

编辑：更多解释

我的理解是，你需要检查是否有与同UsergroupName其他UsergroupMetaData对象。

假设我们会让你的整个班级成为验证不是财产：需要

[UniqueUsergroupName] 
public class UsergroupMetaData 

没有参数。我们来看看UniqueUsergroupName Validate（）方法的外观如何：

public override Boolean IsValid(Object value) 
{ 
    var usergroupName = value != null ? value.ToString() : null; 
    //We don't validate empty fields, the Required validator does that 
    if(string.IsNullOrEmpty(usergroupName)) return true; 

    Type objectType = value.GetType(); 
    //Get the property info for the object passed in. This is the class the attribute is 
    // attached to 
    //I would suggest caching this part... at least the PropertyInfo[] 
    PropertyInfo[] neededProperties = 
    objectType.GetProperties(); 

    var customerIdProperty = neededProperties 
    .Where(propertyInfo => propertyInfo.Name == "CustomerID") 
    .First(); 
    var customerId = (int?) customerIdProperty.GetValue(value, null); 

    var usergroupNameProperty = neededProperties 
    .Where(propertyInfo => propertyInfo.Name == "UsergroupName") 
    .First(); 
    var usergroupName = (string) customerIdProperty.GetValue(value, null); 

    // Now I don't userstand why the blog post author did all this reflection stuff to 
    // get the values of the properties. I don't know why he just didn't d something like: 
    // var usergroup = (Usergroup) value; 
    // var customerId = usergroup.CustomerId; 
    // var usergroupName = usergroup.UsergroupName; 
    // 
    //I think reflection was not needed here. Try both ways anyway. 
    // The next lines should not be different regardless of whether you used reflection. 
    // 

    //We don't validate empty fields, the Required validator does that 
    if(string.IsNullOrEmpty(usergroupName)) return true; 

    //Now you have the customerId and usergroupName. Use them to validate. 
    //If I'm using LINQ (for explanation only) it'd be something like: 
    // Assuming _rep.GetUsergroups() returns IQueryable (only for explanation): 
    int numberOfOtherUsergroupsWithSameName = 
     _rep.GetUsergroups() 
       .Where(g => g.UsergroupName == usergroupName && g.CustomerId != customerId) 
       .Count(); 
    return numberOfOtherUsergroupsWithSameName == 0; 
}